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Table 2 Examination of substrate preferences towards model compounds exhibited by PO containing cell-free extract from A. chroococcum SBUG 1484 compared to fungal crude PO preparations from P. cinnabarinus SBUG-M 1044 and PPO from A. bisporus

From: Study of enzymatic properties of phenol oxidase from nitrogen-fixing Azotobacter chroococcum

  Initial rate of activity (ΔA min-1 mL-1 × factor 1,000)
Model compound Wavelength
[nm]
A. chroococcum PO P. cinnabarinus PO A. bisporus PPO
Compound group 1     
Guaiacol 436 10 28 2
para-Vanillin 436 0a 0 0
ortho-Vanillin 468 40 28 0
Vanillin acid 436 0 0 0
Vanillin alcohol 420 42 0 0
Vanillin azine 468 0 6 0
4-Hydroxy-3-methoxy-α-
methylbenzyl alcohol
420 24 0 0
2-Methoxy-6-methylphenol 468 54 0 0
2-Methoxy-4-methylphenol 420 34 0 0
2-Methoxy-4-propylphenol 420 84 0 0
2-Hydroxy-6-methoxybenzaldehyde 420 0 0 0
2-Hydroxy-5-methoxybenzaldehyde 420 36 4 0
Eugenol 420 76 32 0
Ferulic acid 480 0 0 0
Compound group 2     
2,6-Dimethoxyphenol (2,6-DMP) 468 746 532 20
2,3-Dimethoxyphenol 468 5 0.6 0.2
Syringic acid 468 0.8 0.4 0.4
Syringaldehyde 468 1 0.4 0.2
4-Methyl-2,6-dimethoxyphenol 468 0.6 0.2 0
2,6-Dimethylphenol 468 0.7 1.8 0.6
Syringaldazine 525 0 22.4 0
Compound group 3     
Catechol 450 9 2.5 934
3-Methylcatechol 420 29 30 412
4-Methylcatechol 420 24 8 572
tert-Butylcatechol 420 13 8 886
3-Methoxycatechol 420 13 9 52
3-Isopropylcatechol 420 34 20 362
Hydrocaffeic acid 530 1.5 0 74
Compound group 4     
Hydroquinone 285 0.5 1 0
2-Methylhydroquinone 285 0.5 1.2 0.2
2-Methoxyhydroquinone 285 0.8 2.4 1.2
tert-Butylhydroquinone 285 0.4 1.6 0.8
2,3-Dimethylhydroquinone 400 0.8 0.6 0
2,6-Dimethoxyhydroquinone 400 2.6 3 0
Compound group 5     
4-Hydroxyindole 400 5 6 4
3-(3,4-Dihydroxyphenyl)-L-alanine 475 4 3 388
Tyrosineb 280 0 0 6
Dopamine 400 8 2.3 448
3,4-Dihydroxybenzoic acid 400 0.6 2 8
3,4-Dihydroxyphenylacetic acid 400 1 3 1,072
Compound group 7     
ABTS 420 582 638 18
Pyrogallole 450 108 14 170
para-Phenylenediamine 523 78 90 30
para-Cresol 300 0 0 8
  1. Initial rate of enzyme activity was measured with values shown multiplied by a factor of 1,000.
  2. a Change in absorbance could not be determined within prolonged incubation times, highlighting the compound as a non-enzyme substrate under the conditions applied.
  3. b Assaying the oxidation of tyrosine (compound group 5) and p-cresol (compound group 7) was accomplished after a pre-incubation period of 5 minutes at 25°C.